HF alkylation is a developed and mature technology. In an HF alkylation process olefins, isoparaffins and HF are intimately contacted with each other such as to produce an alkylate. Phase separation and recycling of HF as well as fractionation of the organic phase are known steps in the art.
Generally, the exothermic HF alkylation reaction is carried out with a substantial excess of isoparaffins over the olefins. U.S. Pat. No. 3,006,739 discloses an isobutane to olefin volume ratio of 14.1:1. This large excess of isobutane or other isoparaffin in an HF alkylation process requires a separation of the excess isoparaffin from the alkylate. Usually this is achieved by evaporating the isoparaffin. Such an evaporation of a large volume of isobutane requires not only a significant amount of energy but necessitates fairly large hydrocarbon fractionators.